164 research outputs found
STUDI DI TRANSITORI ELETTROMECCANICI ED ELETTROMAGNETICI PER LINEE MISTE DI TRASMISSIONE AEREOCAVO
No full textSynchronizing Interactions Between Different Types of Grid-Forming Converters in Smart Grids
No full textThe work investigates the transient synchronizing interactions between different types of grid-forming controls. Two well-known grid-forming schemes are implemented and considered for analysis: a droop-based control and a swing-based control. The two controls are examined for a temporary loss of synchronism. The analysis is performed considering two different conditions for the grid interconnecting the converters: a resistive-inductive grid and a mainly inductive grid. The first case corresponds to actual conditions in low and medium voltage applications. The second case is realized with the implementation of a virtual reactance in the grid-forming control scheme. The analysis of the results provides a specific insight on the characteristics of the synchronizing interactions between the different types of grid-forming converters, indicating the possibility of steep reactions, mutual oscillations and unsymmetrical interactions
The 10-Bus Model of the Italian Power System: A Tool for Multi-Site Co-Simulations
No full textThe paper presents the 10-bus model of the Italian power system, with a particular focus on the opportunity of using the model for multi-site co-simulations. The model is a simplified version of the Italian power system, where the main structure of the 380 kV transmission system interconnecting southern and northern Italy is reflected, and the total load and generation are distributed proportionally to the represented regions. The model is developed in MATLAB/Simulink, and it is compiled for real-time simulation with the OPAL-RT technologies. Some possible applications of the model for multi-site distributed co-simulations are introduced and discussed, showing also the suitability of the model in terms of variable multi-site configurations
Transient behaviour of a “mixed” overhead-cable EHV line under lightning events
No full textRecently, in many countries have been undergone or are planning links with AC extra-high voltage (EHV) underground cables. Cable lines offer the possibility of a reduced environment impact and for this reason they are often the only alternative for the reinforcement or the expansion of power system accepted by public opinion. The coexistence of overhead and cable line in the so called ¿mixed¿ lines, however, raises several questions regarding their behaviour both in steady state and in transient. The purpose of this work is to investigate the transient behaviour of a mixed overhead-cable EHV line under lightning events, describing the effects of the following overvoltages on the system. The mixed line analyzed is a known case found in literature: the results obtained by the model are assumed as term of comparison with the known case. The model thus validated is used for further analysis, taking into account different configuration of the mixed system. The events subsequent lightning may be different: the study considers the shielding failure and the direct stroke on tower, with the possibility of back flashover along insulators. The analysis, carried out in PSCAD/EMTDC environment, has shown that shielding failure does not represent a critical event to mixed line and back flashover occurs for fast waveshape and high value of peak current
On the senior authorship of Musca oleae (Diptera: Tephritidae)
No full textPietro Rossi (1738–1804), Professor at the University of Pisa, in 1790 described the olive fruit
fly Musca oleae in his opus Fauna Etrusca and for the next 121 years, Rossi was considered its
author. During all the 900 century, Gmelin was considered the senior author. In this paper we report that the date of Rossi's Fauna Etrusca has
been found to pre-date Gmelin's 13th Edition for the part that includes Musca oleae. Thus, we conclude that the senior author has to be considered definitively
Rossi and not Gmelin
Transient stability assessment of SMIB System with Mixed overhead-cable line – Sensitivity analysis
No full textA blockchain-based architecture for tracking and remunerating fast frequency response
No full textThe increasing penetration of renewable sources introduces new challenges for power systems’ stability, especially for isolated systems characterized by low inertia and powered through a single diesel power plant, such as it happens in small islands. For this reason, research projects, such as the BLORIN project, have focused on the provision of energy services involving electric vehicles owners residential users to mitigate possible issues on the power system due to unpredictable generation from renewable sources. The residential users were part of a blockchain-based platform, which also the Distributors/Aggregators were accessing. This paper describes the integrated framework that was set up to verify the feasibility and effectiveness of some of the methodologies developed in the BLORIN project for fast frequency response in isolated systems characterized by low rotational inertia. The validation of the proposed methodologies for fast frequency response using Vehicle-to-Grid or Demand Response programs was indeed carried out by emulating the dynamic behavior of different power resources in a Power Hardware-in-the-Loop environment using the equipment installed at the LabZERO laboratory of Politecnico di Bari, Italy. The laboratory, hosting a physical microgrid as well as Power Hardware-in-the-Loop facilities, was integrated within the BLORIN blockchain platform. The tests were conducted by assuming renewable generation development scenarios (mainly photovoltaic) and simulating the system under the worst-case scenarios caused by reduced rotational inertia. The experiments allowed to fully simulate users’ interaction with the energy system and blockchain network reproducing realistic conditions of tracking and remuneration of users’ services. The results obtained show the effectiveness of the BLORIN platform for the provision, tracking and remuneration of grid services by electric vehicles and end users, and the benefits that are achieved in terms of reducing the number of diesel generating units that need to be powered on just to provide operational reserve due to the penetration of renewable sources, resulting in fuel savings and reduced emissions
Assessing the Grid Impact of Renewable Energy Communities in a Small Island
No full textThe paper presents a study carried out on the island of Pantelleria aimed at assessing the impact of the rise of renewable energy communities (RECs) on the distribution grid parameters. A comparison of various scenarios is done considering different operational strategies of BESSes and electric storage water heaters and different penetration of photovoltaic systems, whose maximum power is defined according to the Italian requirements for small islands (Decree “Isole minori”). The analysis of the impact on the grid is a key element for the evolution and development of RECs in small islands. The study highlight the beneficial impacts of RECs on the distribution grid if associated with suitable Demand Response strategies
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